The Comet Lovejoy, before perihelion, the nucleus had been estimated to be between 100 and 200 meters in diameter. Since the comet survived perihelion, it is thought that the nucleus must have been larger, perhaps up to 500 meters.<quoted text>
No Surprise should note that the corona is not the Sun. It is a plasma that surrounds the Sun and is still mostly what people would call a vacuum. You spoke of something larger striking the Sun. Striking the Sun is totally different from going through the corona. As a comparison a meteorite may survive a glancing pass through the Earth's upper atmosphere. No meteorite can "survive" by crashing into the Earth.
Now lets take in consideration what if a comet the size of Comet Hyakutake with a nucleus of about 4.8 km (3.0 mi)(4800 meters) across was headed straight for the sun. Comet Lovejoy is less than 1/9th of its size and passed through and survived. Then one the size of Comet Hyakutake would be very damaging if it hit the sun. Not survivable for life on earth.